Since the late 1800s, orthopedic surgeries have been performed to correct and stabilize patients' bony anatomy. While the majority of orthopedic surgeries continue to be performed on knees and hips, procedures on the spine have been increasing since the 1980s, and the number of approaches and procedures continues to expand. Rods, plates, screws, hooks, and interbody fusion spacers are examples of implants currently used align and stabilize patients' spines to address issues with deformity (such as scoliosis), tumor, trauma, or degenerative conditions.
Initially, surgeons treated their patients from a single incision, with a posterior approach. In this orientation, the patient may be positioned prone (on his/her stomach) and the surgeon makes an incision in the person's back. Corrections were made using instruments and implants from that approach, the implants were inserted and/or locked in place, and the incision was closed.
Not long after, anterior approaches started to be utilized. In an anterior approach, the patient may be positioned supine (on his/her back) and an incision is made in the abdomen, in line with where the correction needs to be made. This approach creates new challenges, because in a posterior approach the surgeon is just traversing muscle tissue, but in the anterior approach the surgeon is working near/against the patient's internal organs and vascular structures. The advantage of the anterior approach is that the anterior column of the spine is the primary load-bearing member, and addressing the anterior side directly is thought to allow the surgeon to impart greater correction than via a posterior-only approach.
A lateral approach has also been considered and used. In a lateral approach, the patient is typically positioned in the lateral decubitus position (e.g. on his/her side) and the incision is made approaching the anterior spinal column directly from the side, as opposed to the front as in the anterior approach. This avoids organs, as they tend to “fall forward” and move anteriorly out of the surgeon's field. But the lateral approach may also require addressing the psoas muscle, and within the psoas muscle are housed a bundle of nerve fibers that should be avoided to minimize post-operative complications. Therefore, the lateral approach was not used often until the advent of neural integrity monitoring, which allows the surgeon to monitor via electronic equipment how close they are to these nerves during the lateral approach. The lateral approach has physiologic limitations as well—ribs and the pelvis prevent easy access to levels beyond the upper lumbar region or below the third or fourth lumbar vertebra. However, the ability to place a large load-bearing interbody implant has made the lateral procedure appealing, despite its challenges.
Most recently, an oblique approach has been utilized. The patient may still be positioned laterally, but rather than a true lateral trajectory, the surgeon approaches the anterior from an oblique angle, or “tilted” towards the anterior spine. This allows access to the appropriate discs, yet avoids contact with the psoas (and hidden neural structures) while still avoiding conflict with the internal organs.
Finally, any of the above procedures might be used together in combination. For instance, the surgeon could perform an Oblique Lumbar Interbody Fusion (OLIF) procedure, thus providing a large anterior support structure using an interbody implant, then perhaps follow up with a posterior procedure to provide greater overall stability via posterior implant instrumentation. The surgeon could similarly couple any combination of procedures to accomplish treatment goals in a particular patient. Various approaches to the anterior spine can also be used in combination. For example, because direct lateral exposure does not allow for easy access to the lumbosacral junction (the disc between the lumbar spine and the sacrum or the L5-S1 space) the surgeon could perform an oblique or anterior approach to access that level, and then use direct lateral on the higher (superior) levels. In any event, in order to combine approaches, the surgeon currently has only two choices: reposition the patient during the procedure (while he/she is under anesthesia) or perform separate procedures in series (called “staged procedures”). In the first option, the length of surgery is extended, which is not preferable due to the desire to limit the amount of time that the patient is under anesthesia, and due to Operating Room (O.R.) operational costs added by the delay. Staged procedures may cost more, and typically involve increasing the patient's time in the hospital due to the multiple procedures. The changes in healthcare and/or implementation of the Affordable Healthcare Act (ACA) will likely affect the ability of the surgeon to choose particular combinations as well, given the drive towards cost containment and evidence-based medicine.
Therefore, there remains a clinical need in many cases for the surgeon to be able to utilize several different surgical approaches to the spine either substantially simultaneously or at the very least, during the same procedure. Furthermore, there exists a need for methods and apparatus that allow a surgeon more efficient and efficacious options for treating a patient using several approaches.